Self-locking tubular insert

ABSTRACT

A self-locking tubular insert with an outer screw thread for engaging an outer complementary threaded member and with an inner screw thread for engaging an inner complementary threaded member has a transverse peripheral slot forming a window and a deformable plastic locking element seated in the slot is shaped and sized for compression by the outer complementary member to be bulged thereby inwardly into locking engagement with the inner complementary member.

United States Patent Beidler [4 1 June 20, 1972 54] SELF-LOCKING TUBULARINSERT 3,269,443 8/1966 Coyle ..151/7 [72] lnventor:- Wiflig F B i LaHabra, Calif 3,437,118 4/1969 Coyle 15 H7 [73] Assignee: TreadllneFastener Corporation, Covina, FOREIGN PATENTS OR APPLICATIONS Cahf-1,139,217 l/1969 Great Britain ..151/7 [22] Filed: Oct; 24, 1969 PrimaryExaminer-Edward C. Allen [21] Appl' 869,164 Attorney-Paul A. Weilein 52us. (:1. ..151/7 ABSTRACT Int- ............ Ase f lockin g tubularinsert with an outer screw thread for en- [58] Field of Search ..l51/7gaging an outer complementary threaded member and with an inner screwthread for engaging an inner complementary [56] References Citedthreaded member has a transverse peripheral slot forming a UNITED STATESPATENTS window and a deformable plastic locking element seated in theslot is shaped and sized for compress1on by the outer com- 2,621,69712/1952 McPherson 151/7 plememary member to be bulged thereby w into2,852,056 9/ 1953 Rapula 1 5 V7 locking engagement with the innercomplementary member. 3,173,466 3/1965 Starriett..... ....15l/72,725,915 12/1955 Johnson t. 151/7 17 Claims, 13 Drawing FiguresSELF-LOCKING TUBULAR INSERT BACKGROUND OF THE INVENTION The inventionrelates to a self-locking internally and externally threaded tubularinsert having a transverse peripheral slot with a plastic lockingelement therein of the general do not arise in the use of solid screwsof this type but are en-.

countered in any attempt to provide an internally and externallythreaded tubular insert with such a deformable plastic element forlocking engagement both with a surrounding complementary internallythreaded member and with an inner complementary externally threadedmember.

A troublesome one of these problems is to provide a satisfactoryouter-inner torque differential, i.e., an adequately high ratio betweenthe resistance to rotation of the tubular insert relative to thesurrounding outer complementary member and the resistance to rotation ofthe inner complementary member relative to the tubular insert. If thedifferential is inadequate, any attempt to unscrew the innercomplementary member from the installed tubular insert will be defeatedby unscrewing of the installed insert from the outer complementarymember.

The necessary tolerances in the dimensioning of mating external andinternal screw threads results in variation of the clearances betweenrandomly selected mating threads and therefore the outer-inner torquedifferential must be effective over the expected range of variation insuch clearance. In other words, the' torque differential should not beunduly effected by normal variations in the'clearance between the matingthreads externally of the tubular insert and the mating threadsinternally of the tubular insert.

Another problem peculiar to the use of a tubular insert is to preventthe locking element from being bodily displaced into the interior of thetubular insert when the tubular insert is initially threaded into acomplementary outer threaded member.

Still another problem is to prevent peeling of the locking element andto prevent circumferential displacement of the locking element by therelative advance of the screw thread of the outer complementary member.The difficulty is that the cylindrical wall of a tubular insert isnecessarily quite thin and therefore provides relatively little metalfor anchoring engagement by a plastic locking element.

The present invention is directed to the satisfactory solution of theseproblems as well as other problems relating to a tubular insert that isprovided with a transverse plastic locking element.

SUMMARY OF THE INVENTION A transverse cut is made in the periphery of anexternally and internally threaded tubular insert on a slant to conformto the helix angle of the external thread of the insert to produce aslot having a planar bottom wall that defines a chord of the circularcross section of the insert. The depth of the chordal slot is sufficientto extend slightly into the interior of the tubular plastic, such asnylon, seats in the slot and in a general way conforms to theconfiguration of the slot but extends radially outwardly far enoughbeyond that configuration for the desired locking action. Thus, the slotmay be considered as bounded on its outer side by an imaginary arcuateextension of the outer circumferential surface of the tubular insertincluding extensions of the outer screw thread contours. A lockingelement conforming to the slot configuration as thus defined would havethe same minor and major diameters as the external screw thread of thetubular insert and obviously the locking element must extend radiallyoutward beyond this configuration for locking cooperation with theinternal thread of a surrounding complementary member to create therequired torque resistance. The all essential portion of the plasticlocking element that extends beyond this theoretical outer boundary ofthe slot may be conveniently referredto as the enlargement portion ofthe locking element.

In a well known manner, the required torque resistance between thetubular insert and the surrounding complementary member is created inpart by the locking element crowding the tubular insert laterally intopressure contact with the surrounding complementary member and iscreated in part by the pressure of the enlargement portion of theplastic element against the surrounding complementary member. These twotorque-engendering efiects occur at opposite ends of a diameter thatintersects the above mentioned central radial sector of the slot.

In the practice of the invention that is presently preferred for screwsizes except exceedingly small sizes, the enlargement portion of theplastic locking element is essentially in the form of a central radialprotrusion that lies wholly within the arc of the central radial sectorof the slot, the enlargement being in radial alignment with the window.In effect, the central portion of the locking element in the centralsector of the slot serves as a resiliently outwardly biased radialplunger, the outer end of which may be depressed by the surroundingcomplementary member to displace the plunger longitudinally inwardlyinto locking engagement with the inner complementary member.

It is to be borne in mind that a resilient plastic material such asnylon and such as elastomers, is practically incompressible and beingflowable under substantial pressure are capable of acting hydraulicallyunder pressurized confinement. Since the plastic material is, in effect,trapped under pressure in the two flanking sectors of the slot, theplastic material in the two flanking sectors act as hydraulic brakeshoes against the surrounding complementary member. ln addition, thepressure of the plastic material in the two flanking; sectors againstthe corresponding portions of the bottom wall of the slot create lateralpressure against the tubular insert that crowds the tubular insertdiametrically against the opposite wall of the surrounding complementarymember.

The plastic material in the central sector acts as a hydraulic brakeshoe against the outer complementary member but at the same time pressesradially inwardly against the inner complementary member which in turnacts against the tubular insert to assist in pressing the tubular insertdiametrically against the surrounding complementary member. The lockingaction on the inner complementary member is on the previously mentionedbisecting diameter, the locking action being in part the brake action ofthe inwardly displaced plastic material against the inner complementarymember and in part the metal-to-metal pressure created by thediametrical crowding of the inner complementary member against the innercircumferential wall of the tubular insert.

It is apparent that the desired high outer-inner torque differential isinherent in the described relationships inasmuch as the pressure of theplastic material in the two flanking sectors of the slot is directedsolely to the creation of the outer torque and the plastic pressure inthe central sector of the slot that creates the inner torque alsocontributes to the outer torque in adding to the metal-to-metal pressureof the tubular insert against the outer complementary member. lt isalsoto be noted that resiliently distorting the plastic material within itselastic limits in the central sector against the inner complementarymember involves storing substantial energy in the form of stress in thebody of the plastic material with the result that only a portion of thepressure applied by the outer complementary member is transmitted to theinner complementary member.

It has been found that the described relationships make the self-lockingaction effective over a wide range of tolerances with a desirably hightorque differential over the entire range.

The plastic locking element is formed with screw thread portions on itsouter side that substantially register with a corresponding portion ofthe external thread of the tubular insert at the opposite ends of theslot. The central radial protrusion of the plastic body is in effectsuperimposed on the outer formed screw thread portions of the plasticbody, the radial protrusion spanning the valleys of the outer formedthreads and preferably extending outwardly slightly beyond the majordiameter of the external thread of the tubular insert. Forming theplastic body with thread portions on its outer side achieves thesolution of preventing the outer complementary member from peeling theplastic body away from the bottom wall of the slot or tearing theplastic body or circumferentially displacing the plastic body.

The inner surface of the plastic locking element may also be formed withscrew thread portions to match the corresponding portions of theinternal screw thread of the tubular insert. In one practice of theinvention, however, the inner side of the plastic body simply conformsto the chordal plane of the bottom wall of the slot and in anotherpractice of the invention the inner surface of the plastic lockingelement is cylindrical and approximates the minor diameter of theinternal screw thread of the tubular insert.

In a practice of the invention that is preferred for very small tubularinserts, for example, a tubular insert of the size of a 2-56 screw, theouter enlargement portion of the plastic body is not confined to thecentral sector of the slot but rather is extended over all threesectors..Since the enlargement portion has such a circumferentialextent, it has a lesser radial dimension than a concentrated centralprotrusion and may lie well within the major diameter of the externalscrew thread of the tubular insert. This concept is carried out byforming the screw thread portions on the outer periphery of the plasticbody with valleys that are substantially shallower than the valleys ofthe corresponding external screw thread of the tubular insert. Thus, theessential enlargement portion of the plastic body that extends outwardlybeyond the heretofore defined slot configuration is in the form ofmaterial aligned with the valleys of the external screw thread of thetubular insert, the material of the enlargement portion lying betweenthe major and minor diameters of the external screw thread of thetubular insert.

As heretofore stated, the chordal slot preferably conforms to the helixangle of the external screw thread of the tubular body. For sizes of thetubular insert of 6-32 and larger the transverse slot may approximatethe width of two turns of the external screw thread of the tubularinsert. Preferably such a slot extends from the crest of one turn of theexternal screw thread to the crest of a turn that is two turns removedfrom the one turn. In sizes smaller than 6-32, the transverse slot maybe of the width of only one turn of the external screw thread of thetubular insert, the slot extending from the crest of one turn of theexternal thread of the tubular insert to the crest of the next adjacentturn of the external thread.

The features and advantages of the invention may be understood from thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view partlyin section of a selflocking insert embodying a construction inaccordance with the present invention;

FIG. 2 is a transverse section taken along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged portion of FIG. 2;

FIG. 4 is an enlarged section along the line 44 of FIG. 1;

FIG. 5 is a transverse sectional view showing the cylindrical body ofFIG. 1 installed in an internally threaded complemental member;

FIG. 6 is a similar view with an externally threaded inner complementarymember threaded into the tubular insert;

FIG. 7 is a section on a reduced scale along the line 77 of FIG. 6;

FIG. 8 is a fragmentary elevation of an alternate embodiment of theinvention;

FIG. 9 is a transverse sectional view taken along the line 9- 9 of FIG.8;

FIG. 10 is a fragmentary longitudinal sectional view taken through aperipheral portion of the alternate embodiment of FIG. 8;

FIG. 11 is a fragmentary transverse sectional view illustrating anotherembodiment of the invention;

FIG. 12 is a similar view of still another embodiment of the invention;and

FIG. 13 is a diagram for the purpose of explaining the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The underlyingconcept of the invention may be understood by referring first to thediagram of FIG. 13 which represents an externally and internallythreaded tubular insert, generally designated 10, having a transverseslot with a bottom wall 12 in a plane that conforms to a chord of thecircular configura tion, the slot being cut on a slant to align with thehelical turns of the outer screw thread. The slot penetrates theinterior of the tubular insert slightly to form a window 14 in thetubular wall of the insert which is of substantially less width than thelength of the bottom wall of the slot. In this instance, the width ofthe window is no greater than one-third the length of the bottom wall ofthe slot.

The opposite edges of the window 14 determine two radial lines whichdefine a previously mentioned central sector 15 of the slot and the twoside edges of the window together with the corresponding opposite endsof the slot determine radial lines which define two flanking sectors 16.

The configuration and volume of the slot will be considered asdetermined by an imaginary extension across the slot of the outercircumferential surface of the tubular insert including extensions ofthe turns of the outer screw thread of the insert. Thus, if aresiliently deformable locking element generally designated 18 andrepresented by stippling in FIG. 13 were to conform precisely to thisdefined configuration of the slot, it would merely replace the metalthat has been removed to form the slot and would not be of sufficientradial dimension to provide a self-locking action. Obviously, theplastic locking element 18 must extend outwardly beyond theconfiguration of the slot sufficiently to accomplish two purposes, firstto take up all of the clearance between the tubular insert and any outercomplementary threaded member into which the insert may be installed,and second, to exert pressure on the inner circumferential wall of theouter complementary member for the desired self-locking action.

The purpose of the insert 18 that extends radially outwardly beyond thedefined configuration of the slot will, for convenience, be referred toas the enlargement portion. In the preferred practice of the inventionfor all sizes of the insert except the smaller sizes, the enlargementportion of the insert is primarily in the form of a radial protrusion 20that is outlined by an arcuate dot-dash line. It is to be noted that theenlargement portion 20 lies wholly within the central sector 15 and inthis instance the enlargement portion is symmetrical to a diameter thatbisects the central sector. In some instances the rest of the lockingelement 18 extends slightly beyond the outer boundary of the slot asindicated by dotted lines 22 and these flanking portions of theenlargement may function to take up at least some of the clearancebetween the tubular insert and the surrounding outer complementarymember rather than to provide self-locking action. As will be explained,however, the central protrusion 20 is preferably omitted in anyexceedingly small tubular insert, for example, an insert of the size2-56, the self-locking action being then accomplished by an enlargementof the general configuration indicated by the dotted lines 22.

When the tubular insert is installed in an outer complementary memberhaving an internal screw thread, the radial protrusion is depressed andcrowds the tubular insert laterally against the surroundingcomplementary member to result in two different locking effects whichoccur at opposite ends of the diameter that bisects the central sector15. One of these effects is the metal-to-metal pressure of the tubularinsert against the inner circumferential wall of the outer complementarymember in the region that is diametrically opposite from the radialprotrusion 20 and, of course, the other locking effect is accomplishedby the resiliently deformed protrusion 20 exerting radial outwardpressure against the surrounding complementary member to serve in effectas a brake shoe.

The direction of least resistance to flow or displacement of the plasticmaterial is radially inward from the central sector 15, the plasticmaterial being displaced or bulged radially inwardly through the window14 as indicated by the dotted line 24 for locking action againstwhatever inner complementary member may be threaded into the tubularinsert.

The pressure that is built up in this manner in the central sector 15 istransmitted to the two flanking sectors 16, the pressure being exertedin all directions as indicated by the arrows. There is some tendency forthe plastic material when highly pressurized to be extrudedcircumferentially along the clearance space at the two ends of the slotas indicated by the two arrows 25, but the resistance to such extrusionis of exceedingly high magnitude. There is also a tendency for thepressurized plastic material in the two flanking sectors 16 to bediverted towards the window 14 by the bottom wall 12 of the slot asindicated by the arrows 26. In the main, however, the plastic materialin the two flanking sectors 16 behaves as a trapped pressurized fluidand the plastic material in the two flanking sectors function ashydraulic brake shoes against the surrounding complementary member.Thus, the plastic body provides outwardly acting brake shoes in thethree radial sectors of the slot and functions as an inwardly actingbrake shoe only in the central sector. It is apparent that by virtue ofthis fact the described structure inherently provides a desirably highouter-inner torque differential. It is to be noted that the brakingthrust inwardly of the plastic of the central sector against the innercomplementary member shifts the inner complementary member diametricallyinto locking pressure against the inner circumferential wall of thetubular insert and this diametrical thrust adds to the diametricalthrust of the tubular insert against the surrounding outer complementarymember to favor the desired high torque diiferential.

The self-locking action is effective throughout the whole range ofclearances that are encountered in the random mating of threaded parts.At one extreme the clearance between a tubular insert and thesurrounding complementary member is at maximum where the pitch diameterof the internal screw of the outer complementary member is at themaximum in the range of permitted tolerance and the pitch diameter ofthe external screw thread of the tubular insert is at the minimum in thepermitted range of tolerance. At the other extreme of the range, theclearance between the tubular insert and the surrounding complementarymember is at a minimum with the pitch diameter of the internal thread ofthe outer complementary member at the minimum in its range of toleranceand the pitch diameter of the external screw thread of the tubularinsert 10 at the maximum in its range of tolerance.

An important factor in the adaptability of the plastic locking elementto the wide range of clearance between the tubular insert and thesurrounding complementary member is that the radial protrusion 20extends over only a minor portion of the circumferential extent of theplastic body and being relatively narrow is relatively free to spreadcircumferentially in opposite directions to compensate for variations inthe clearance.

FIGS. 1 to 4 indicate the construction of an embodiment of the inventionthat is preferably used for all tubular insert sizes except the smallersizes. The insert. which is generally designated 27 has a chordal slot28 which, as shown, is inclined in alignment with the turns of theexternal screw thread of the insert and which is of the width of twoscrew threads, extending from the crest of one screw thread across asecond adjacent screw thread to the crest of a third screw thread.

A locking element 29 of suitable plastic material occupies the chordalslot and on its radially outward side is formed with screw threadportions 31, 32, and 33 which substantially'register with correspondingscrew portions of the external thread of the tubular insert at theopposite ends of the chordal slot.

As shown in FIG. 3, the crests of the formed thread portions of thelocking element extend slightly outwardly beyond the major diameter 34of the external screw thread of the tubular insert but the lockingaction of the plastic body is accomplished primarily by a central radialprotrusion 35 which, as shown in FIG. 3, extends radially beyond themajor diameter 34 and as shown in FIG. 1 extends across the two valleysof the formed thread portions 3l-33 of the plastic body.

As shown in FIG. 3 the chordal slot 28 is deep enough to penetrate theinterior of the tubular insert and thereby form a window 36 whichdivides the bottom wall 38 of the chordal slot into two spaced parts.

Providing the locking element 29 with the thread portions 31-33facilitates screw threaded advance of the internal screw thread of theouter complementary member across the plastic body and thus eliminatesany tendency for the plastic body to be peeled away from a bottom wall38 or to be sheared or to be circumferentially displaced.

In this particular embodiment of the invention the inner circumferentialsurface of the plastic locking element 29 is further provided withformed thread portions 41, 42, and 43 that match the adjacent threadportions of the internal screw thread of the tubular insert at oppositesides of the window 36.

FIG. 5 shows the tubular insert 27 installed in a surrounding internallythreaded complementary body 45 which may be a nut or may be a plate orcasting. Since the window in the cylindrical wall of the insert 27 iscut across the internal screw thread of the insert, the window varies inwidth, being relatively narrow where the window intersects a turn oftheinternal screw thread of the tubular insert, as shown in FIGS. 2 and3, and being relatively wide where the window intersects a valleybetween two turns of the internal screw thread. FIG. 5 shows by anarcuate line 46 how the plastic material bulges radially inwardly wherethe window is relatively narrow and shows by a longer arcuate line 48how the plastic material bulges inwardly where the window is relativelywide at the intersection of a valley of the internal screw thread of thetubular insert.

FIGS. 6 and 7 show how an externally threaded inner complementary memberin the form of a screw 50 may be threaded into the installed tubularinsert 27 and locked therein by the inwardly bulging plastic material ofthe locking element 29.

In the presently preferred practice of the invention tubular insertsizes 6-32 and larger are constructed as indicated in FIGS. 1-4 with thechordal slot and the locking element therein of a width of two turns ofthe external screw thread of the tubular insert as heretofore described.Tubular inserts smaller than 6-32 and larger than 256 are of the sameconstruction with a central radial protrusion but the slots and thelocking elements therein are of a width of only one turn of the externalscrew threadinstead of being the width of two turns.

Preferably, the smallest sized insert 2-56 is of a width of only oneturn of the external screw thread of the tubular insert and the lockingelement in the slot does not have a previously described centralprotrusion. Such a construction is shown in FIGS. 8-10.

In the second embodiment of the invention shown in FIGS. 8, 9, and 10,an internally and externally threaded tubular insert 52 has a slanted,transverse peripheral slot 54 of the character heretofore describedwhich is of a width of only one turn of the external screw thread of thetubular insert. The slot extends from one crest of an external screwthread across a valley to the crest of the next turn as may be seen inFIG. 8.

A plastic locking element 55 seated in the chordal slot 54 is formedwith external thread portions 56 and 57 that substantially register withcorresponding portions of the outer screw thread of the tubular insertat the opposite ends of the slot. As shown in FIGS. 9 and 10, thelocking element 55 is further formed with internal thread portions 58and 59 which register with corresponding portions of the internal screwthread of the tubular insert.

In this second embodiment of the invention the enlargement portion ofthe plastic locking element is of the character indicated by the dottedline 22 in FIG. 13 instead of being of the character of a central radialprotrusion. The enlargement portion, i.e., the portion that liesradially outwardly from the previously defined configuration of thechordal slot 54 is located in the valley that is bound by the outerthread portions 56 and 57 of the locking element. For this purpose thevalley 60 of the exterior of the locking element is of less depth thanthe valleys 62 formed by the external screw thread of the insert, as maybe seen in FIG. 10.

The difference between the depths of the valleys 60 and 62 providessufficient plastic material outside of the configuration of the slot totake up the maximum clearance that may occur between the tubular insertand the surrounding complementary member and in addition providessufi'rcient material to cooperate with the inner circumferential surfaceof the surrounding complementary member to create the heretoforedescribed locking action.

FIG. 11 illustrates a modification of the invention in which a plasticlocking element 64 is of the same construction as the locking element 29in the first embodiment of the invention except for the fact that aninner side 65 of the plastic locking element is in the same chordalplane as the slot and extends straight across the window in the tubularwall as shown. Thus, the inner side 65 of the plastic locking elementinterferes with the external thread of an inner complementary member,the pressure of the inner side of the locking element against the innercomplementary member being augmented by the usual radially outwardprotrusion 66.

FIG.. 12 shows another modification of the invention wherein a plasticlocking element 68 has the usual radial protrusion 70 but the innersurface 72'of the insert is cylindrically curved to conformapproximately to the minor diameter of the internal screw thread of thetubular member. Thus, the radially inner side of the locking element 68interferes with the external screw thread of an inner complementarymember with the pressure of the plastic material against the innercomplementary member augmented by the action of the radial protnision70.

The description in specific detail of the selected embodiments of theinvention will suggest various changes, substitutions and otherdepartures from the disclosure within the spirit and scope of theinvention.

lclaim:

1. In an internally and externally threaded tubular insert designed tocreate torque resistance between the tubular insert and an innercomplementary threaded member and to create substantially greater torqueresistance between the tubular insert and an outer complementarythreaded member, the combination of,

an elongate slot in the tubular insert having a greater length thanwidth, said slot being positioned with its length axis transverse to theaxis of the insert and forming a central window in the cylindrical wallof the insert, with two generally flat portions of the bottom wall ofthe slot spaced apart by the window and extending in opposite lateraldirections from the window in generally coplanar relation,

the opposite sides of the window defining a transverse central radialsector and the opposite sides of the window together with thecorresponding opposite ends of the slot forming two transverse radialsectors flanking the central sector; and

a transversely extending locking element of deformable material seatedin the slot with opposite end portions against the bottom wall portionsthereof and spanning the window,

said locking element occupying the space in the slot that is bounded bythe imaginary extension of the outer circumferential surface of thetubular insert across the slot,

said locking element extending radially outwardly beyond the outerboundary of the slot to cooperate lengthwise with a portion of the innercircumferential surface of an outer complementary member thereby todisplace the tubular insert laterally against the diametrically oppositeportion of the inner circumferential surface of the outer complementarymember,

whereby threading the tubular insert into an outer complementary membertraps the material of the locking element in said flanking sectors ofthe slot and places the material of the locking element under comprexionwith the lines of least flow resistance of the material extendingthrough the window to cause the locking element to bulge inwardly of thewindow into locking engagement with an inner complementary member thatis threaded into the tubular insert.

2. In an internally and externally threaded tubular insert designed tocreate torque resistance between the tubular insert and an innercomplementary threaded member and to create substantially greater torqueresistance between the tubular insert and an outer complementarythreaded member, the combination of:

an elongate slot in the tubular insert having a greater length thanwidth, said slot being positioned with its length axis transverse to theaxis of the insert and forming a central window in the cylindrical wallof the insert, with two portions of the bottom wall of the slot spacedapart by the window and extending in opposite lateral directions fromthe window,

the opposite sides of the window defining a transverse central radialsector and the opposite sides of the window together with thecorresponding opposite ends of the slot forming two transverse radialsectors flanking the central sector; and

a transversely extending locking element of deformable material seatedin the slot with opposite end portions against the bottom wall portionsthereof and spanning the window,

said locking element occupying the space in the slot that is bounded bythe imaginary extension of the outer circumferential surface of thetubular insert across the slot, including extensions of the outer threadof the tubular insert, and

said locking element having a radial protrusion located in said centralsector and extending radially outwardly beyond the outer boundary of theslot to cooperate lengthwise with a portion of the inner circumferentialsurface of the outer complementary member to displace the tubular insertlaterally against the diametrically opposite portion of the innercircumferential surface of the outer complementary member, andcompensate for the inward bulge of the locking material inwardly of thewindow to maintain a high torque resistance with the outer complementarymember,

whereby threading the tubular insert into an outer complementary membertraps the material of the locking element in said flanking sectors ofthe slot and places the material of the locking element under compresionwith the lines of least flow resistance of the material extendingthrough the window to cause the locking element to bulge inwardly of thewindow into locking engagement with an inner complementary member thatis threaded into the tubular insert.

3. A combination as set forth in claim 2 in which the radially outerside of the locking element is formed with portions of screw threads atits opposite ends substantially registering with portions of theexternal screw thread of the tubular insert at the opposite ends of theslot, said protrusion being devoid of threads and extending across thevalleys of the formed portions of screw threads.

4. A combination as set forth in claim 3 in which the inner radial sideof the locking element is formed with portions of screw threads thatsubstantially register with adjacent portions of the internal screwthreaded tubular insert.

5. A combination as set forth in claim 3 in which said protrusionextends from the minor diameter of the formed portions of screw threadsradially outward beyond the major diameter of the formed portions ofscrew threads.

6. A combination as set forth in claim 3 in which said slot is inclinedin alignment with the helical turns of the external screw thread of thetubular insert and is of a width of at least one turn of the externalscrew thread of the tubular insert.

7. A combination as set forth in claim 6 in which the width of the slotand the locking element therein is approximately the width of two turnsof the external screw thread of the tubular member.

8. A combination as set forth in claim 7 in which saidslot extends inwidth from the crest of one turn of the external screw thread of thetubular insert to the crest of a turn that is two turns removed fromsaid one turn.

9. A combination as set forth in claim 2 in which the bottom wall of theslot conforms to a chord of the circular cross sectional configurationof the tubular insert and in which the inner side of the locking elementconforms to the same chord.

10. A combination as set forth in claim 9 in which the outer side of thelocking element is formed with portions of screw threads substantiallyregistering with portions of the external screw thread of the tubularinsert at opposite ends of the slot.

11. A combination as set forth in claim 3 in which the inner side of thelocking element that spans the window is of cylindrical configurationcorresponding approximately to the minor diameter of the internal screwthread of the tubular in- 12'. In an internally and externally threadedtubular insert designed to create torque resistance between the tubularinsert and an inner complementary threaded member and to createsubstantially greater torque resistance between the tubular insert andan outer complementary threaded member, the combination of:

anelongate slot in the tubular insert having its length axis positionedtransverse to the axis of the insert forming a central window in thecylindrical wall of the insert, two generally flat portions of thebottom wall of the slot being spaced apart by the window and extendingin opposite lateral directions from the window in generally coplanarrelation,

the opposite sides of the window defining a central radial sector andthe opposite sides of the window together with the correspondingopposite ends of the slot forming two radial sectors flanking thecentral sector; and a locking element of deformable material seated inthe slot against the bottom wall thereof and spanning the window,

said locking element occupying the space in the slot that is bounded bythe imaginary extension of the outer circumferential surface of thetubular insert across the slot including extensions of the outer threadof the tubular insert,

said locking element being fonned with external portions of screwthreads extending along the lengths axis and substantially registeringwith adjacent portions of the external screw thread of the tubularinsert at opposite ends of the slot,

whereby a peripheral portion of the locking element lies between themajor and minor diameters of the external screw thread of the insert,

said locking element being further formed with the inner side thereofthat spans the window havin at least a portron thereof correspondingapproximate y to the minor diameter of the internal screw thread of theinsert,

whereby threading the tubular insert into a complementary outer membercauses the screw thread of the outer complementary member to displacesaid peripheral portion of the locking element radially inwardly toplace the locking element under compression,

the volume of said peripheral portion being selected to cause thecompressed locking element to bulge inwardly through the window intolocking engagement with an inner complementary member. 13. In aninternally and externally threaded tubular insert designed to createtorque resistance between the tubular insert and an inner complementarythreaded member and to create substantially greater torque resistancebetween the tubular insert and an outer complementary threaded member,the combination of:

an elongate slot in the tubular insert having its length axis positionedtransverse to the axis of the insert forming a central window in thecylindrical wall of the insert, two generally flat portions of thebottom wall of the slot being spaced apart by the window and extendingin opposite lateral directions from the window in generally coplanarrelation,

the opposite sides of the window defining a central radial sector andthe opposite sides of the window together with the correspondingopposite ends of the slot forming two radial sectors flanking thecentral sector; and a locking element of deformable material seated inthe slot against the bottom wall thereof and spanning the window,

said locking element occupying the space in the slot that is bounded bythe imaginary extension of the outer circumferential surface of thetubular insert across the slot including extensions of the outer threadof the tubular insert,

said locking element being formed with external portions of screwthreads extending along its length axis and substantially registeringwith adjacent portions of the external screw thread of the tubularinsert at opposite ends of the slot but with the valleys of the formedthread portions substantially shallower than the valleys of the adjacentportions of the external screw thread of the tubular insert,

whereby a peripheral portion of the locking element lies outside saidextended outer circumferential surface of the tubular insert and liesbetween the major and minor diameters of the external screw thread ofthe insert,

whereby threading the tubular insert into a complementary outer membercauses the screw thread of the outer complementary member to displacesaid peripheral portion of the locking element radially inwardly toplace the locking element under compression, the volume of saidperipheral portion being selected to cause the compressed lockingelement to bulge inwardly through the window into locking engagementwith an inner complementary member.

14. A combination as set forth in claim 13 in which said locking insertis formed on its inner side with portions of screw threads substantiallyregistering with corresponding portions of the internal screw thread ofthe tubular insert.

15. A combination as set forth in claim 13 in which said slot isinclined into alignment with the turns of the external screw thread ofthe tubular insert.

16. A combination as set forth in claim 15 in which the width of theslot is substantially the width of a single turn of the external threadof the tubular insert.

17. A combination as set forth in claim 16 in which the slot extends inwidth from substantially the crest of one turn of an external screwthread of the tubular insert to substantially the crest of a nextadjacent turn.

* III Patent No 3,670,794 Dated June 20, 1972 inventor) William F.Beidler It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

On the from; page, the assignee of record should read Thr'eadlineFastener Corporation--.

Signeda ndrsealed this 31st day of October 1972.

} (SEAL) Attest:

EDWARD M.FLET( 3I-IER,JR. 7 ROBERT GOTTSGHALK Attestlng OfflcerCommissioner of Patents FORM PO-105O (10-69)

1. In an internally and externally threaded tubular insert designed tocreate torque resistance between the tubular insert and an innercomplementary threaded member and to create substantially greater torqueresistance between the tubular insert and an outer complementarythreaded member, the combination of, an elongate slot in the tubularinsert having a greater length than width, said slot being positionedwith its length axis transverse to the axis of the insert and forming acentral window in the cylindrical wall of the insert, with two generallyflat portions of the bottom wall of the slot spaced apart by the windowand extending in opposite lateral directions from the window ingenerally coplanar relation, the opposite sides of the window defining atransverse central radial sector and the opposite sides of the windowtogether with the corresponding opposite ends of the slot forming twotransverse radial sectors flanking the central sector; and atransversely extending locking element of deformable material seated inthe slot with opposite end portions against the bottom wall portionsthereof and spanning the window, said locking element occupying thespace in the slot that is bounded by the imaginary extension of theouter circumferential surface of the tubular insert across the slot,said locking element extending radially outwardly beyond the outerboundary of the slot to cooperate lengthwise with a portion of the innercircumferential surface of an outer complementary member thereby todisplace the tubular insert laterally against the diametrically oppositeportion of the inner circumferential surface of the outer complementarymember, whereby threading the tubular insert into an outer complementarymember traps the material of the locking element in said flankingsectors of the slot and places the material of the locking element undercompression with the lines of least flow resistance of the materialextending through the window to cause the locking element to bulgeinwardly of the window into locking engagement with an innercomplementary member that is threaded into the tubular insert.
 2. In aninternally and externally threaded tubular insert designed to createtorque resistance between the tubular insert and an inner complementarythreaded member and to create substantially greater torque resistancebetween the tubular insert and an outer complementary threaded member,the combination of: an elongate slot in the tubular insert having agreater length than width, said slot being positioned with its lengthaxis transverse to the axis of the insert and forming a central windowin the cylindrical wall oF the insert, with two portions of the bottomwall of the slot spaced apart by the window and extending in oppositelateral directions from the window, the opposite sides of the windowdefining a transverse central radial sector and the opposite sides ofthe window together with the corresponding opposite ends of the slotforming two transverse radial sectors flanking the central sector; and atransversely extending locking element of deformable material seated inthe slot with opposite end portions against the bottom wall portionsthereof and spanning the window, said locking element occupying thespace in the slot that is bounded by the imaginary extension of theouter circumferential surface of the tubular insert across the slot,including extensions of the outer thread of the tubular insert, and saidlocking element having a radial protrusion located in said centralsector and extending radially outwardly beyond the outer boundary of theslot to cooperate lengthwise with a portion of the inner circumferentialsurface of the outer complementary member to displace the tubular insertlaterally against the diametrically opposite portion of the innercircumferential surface of the outer complementary member, andcompensate for the inward bulge of the locking material inwardly of thewindow to maintain a high torque resistance with the outer complementarymember, whereby threading the tubular insert into an outer complementarymember traps the material of the locking element in said flankingsectors of the slot and places the material of the locking element undercompression with the lines of least flow resistance of the materialextending through the window to cause the locking element to bulgeinwardly of the window into locking engagement with an innercomplementary member that is threaded into the tubular insert.
 3. Acombination as set forth in claim 2 in which the radially outer side ofthe locking element is formed with portions of screw threads at itsopposite ends substantially registering with portions of the externalscrew thread of the tubular insert at the opposite ends of the slot,said protrusion being devoid of threads and extending across the valleysof the formed portions of screw threads.
 4. A combination as set forthin claim 3 in which the inner radial side of the locking element isformed with portions of screw threads that substantially register withadjacent portions of the internal screw threaded tubular insert.
 5. Acombination as set forth in claim 3 in which said protrusion extendsfrom the minor diameter of the formed portions of screw threads radiallyoutward beyond the major diameter of the formed portions of screwthreads.
 6. A combination as set forth in claim 3 in which said slot isinclined in alignment with the helical turns of the external screwthread of the tubular insert and is of a width of at least one turn ofthe external screw thread of the tubular insert.
 7. A combination as setforth in claim 6 in which the width of the slot and the locking elementtherein is approximately the width of two turns of the external screwthread of the tubular member.
 8. A combination as set forth in claim 7in which said slot extends in width from the crest of one turn of theexternal screw thread of the tubular insert to the crest of a turn thatis two turns removed from said one turn.
 9. A combination as set forthin claim 2 in which the bottom wall of the slot conforms to a chord ofthe circular cross sectional configuration of the tubular insert and inwhich the inner side of the locking element conforms to the same chord.10. A combination as set forth in claim 9 in which the outer side of thelocking element is formed with portions of screw threads substantiallyregistering with portions of the external screw thread of the tubularinsert at opposite ends of the slot.
 11. A combination as set forth inclaim 3 in which the inner side of the locking element that spans thewindow is of cylindRical configuration corresponding approximately tothe minor diameter of the internal screw thread of the tubular insert.12. In an internally and externally threaded tubular insert designed tocreate torque resistance between the tubular insert and an innercomplementary threaded member and to create substantially greater torqueresistance between the tubular insert and an outer complementarythreaded member, the combination of: an elongate slot in the tubularinsert having its length axis positioned transverse to the axis of theinsert forming a central window in the cylindrical wall of the insert,two generally flat portions of the bottom wall of the slot being spacedapart by the window and extending in opposite lateral directions fromthe window in generally coplanar relation, the opposite sides of thewindow defining a central radial sector and the opposite sides of thewindow together with the corresponding opposite ends of the slot formingtwo radial sectors flanking the central sector; and a locking element ofdeformable material seated in the slot against the bottom wall thereofand spanning the window, said locking element occupying the space in theslot that is bounded by the imaginary extension of the outercircumferential surface of the tubular insert across the slot includingextensions of the outer thread of the tubular insert, said lockingelement being formed with external portions of screw threads extendingalong the lengths axis and substantially registering with adjacentportions of the external screw thread of the tubular insert at oppositeends of the slot, whereby a peripheral portion of the locking elementlies between the major and minor diameters of the external screw threadof the insert, said locking element being further formed with the innerside thereof that spans the window having at least a portion thereofcorresponding approximately to the minor diameter of the internal screwthread of the insert, whereby threading the tubular insert into acomplementary outer member causes the screw thread of the outercomplementary member to displace said peripheral portion of the lockingelement radially inwardly to place the locking element undercompression, the volume of said peripheral portion being selected tocause the compressed locking element to bulge inwardly through thewindow into locking engagement with an inner complementary member. 13.In an internally and externally threaded tubular insert designed tocreate torque resistance between the tubular insert and an innercomplementary threaded member and to create substantially greater torqueresistance between the tubular insert and an outer complementarythreaded member, the combination of: an elongate slot in the tubularinsert having its length axis positioned transverse to the axis of theinsert forming a central window in the cylindrical wall of the insert,two generally flat portions of the bottom wall of the slot being spacedapart by the window and extending in opposite lateral directions fromthe window in generally coplanar relation, the opposite sides of thewindow defining a central radial sector and the opposite sides of thewindow together with the corresponding opposite ends of the slot formingtwo radial sectors flanking the central sector; and a locking element ofdeformable material seated in the slot against the bottom wall thereofand spanning the window, said locking element occupying the space in theslot that is bounded by the imaginary extension of the outercircumferential surface of the tubular insert across the slot includingextensions of the outer thread of the tubular insert, said lockingelement being formed with external portions of screw threads extendingalong its length axis and substantially registering with adjacentportions of the external screw thread of the tubular insert at oppositeends of the slot but with the valleys of the formed thread portionssubstantially shallower than The valleys of the adjacent portions of theexternal screw thread of the tubular insert, whereby a peripheralportion of the locking element lies outside said extended outercircumferential surface of the tubular insert and lies between the majorand minor diameters of the external screw thread of the insert, wherebythreading the tubular insert into a complementary outer member causesthe screw thread of the outer complementary member to displace saidperipheral portion of the locking element radially inwardly to place thelocking element under compression, the volume of said peripheral portionbeing selected to cause the compressed locking element to bulge inwardlythrough the window into locking engagement with an inner complementarymember.
 14. A combination as set forth in claim 13 in which said lockinginsert is formed on its inner side with portions of screw threadssubstantially registering with corresponding portions of the internalscrew thread of the tubular insert.
 15. A combination as set forth inclaim 13 in which said slot is inclined into alignment with the turns ofthe external screw thread of the tubular insert.
 16. A combination asset forth in claim 15 in which the width of the slot is substantiallythe width of a single turn of the external thread of the tubular insert.17. A combination as set forth in claim 16 in which the slot extends inwidth from substantially the crest of one turn of an external screwthread of the tubular insert to substantially the crest of a nextadjacent turn.